Method of making a thermal insulating unit



April 19, 1938. E. R. POWELL METHOD OF MAKING A THERMAL INSULATING UNIT Filed April 17, 1954 INVENTOR Edward R.POWell.

ATTORN EY.

Patented A 19, 1938 METHOD OF MAKING A THERMAL'INSULA ING UNIT Edward R. Powell, Alexandria, Ind., assignor to Johns-Manville Corporation, New York, N. 2., a corporation of New York Application April 17, 1934, Serial No. 720,979

1 Claim.

This invention relates to a thermal insulating unit and the method of making the same, and particularly to a unit adapted for use at temperatures below the dew-point of vapor in the surrounding atmosphere.

It is an object of this invention to provide a preformed heat insulating bat of mineral wool fibers which is durable and especially light, fiufiy and springy in character, and which will expand and snugly fill all portions of a casing, when compressed therein, and maintain its position indefinitely in the casing when anchored thereto without settling or crumbling of the fibers, thereby adapting it for uses in which it is subjected to jarring and constant mechanical'vibrations.

The invention is illustrated in the drawing in which,

Fig. 1 shows a side elevational view of a unit representing the preferred embodiment of the invention, in part broken away for clearness of illustration;

Fig. 2 shows the casing material, in open form, to be shaped into the case shown in Fig. 1; 1

Fig. 3 shows a cross sectional view on line 33 of Fig. 1;

Fig. 4 shows a cross sectional view of the wall of the case;

Fig. 5 shows a side elevational view of a modification of the invention in which a filler bat is secured to the case by stitching, the structure being broken away in part for clearness of illustration;

Fig. 6 shows a cross sectional view on line 6-6 of Fig. 5; and

a Fig. 7 shows a cross sectional view on line "I-'I of Fig. 5. 1

In the various figures like reference characters denote like parts. J

There is shown a lightweight pad or bat In, of felted fibrous material, enclosed within a moisture-proof and draft-proof case I l. The felt is resilient and contacts with the case.

The case is relatively still and its walls include, suitably, composited sheets of plane and corrugated paper. Thus, the walls may include the corrugated sheet I2, adhered to one or more facing sheets it of plane paper, to form either single-faced or double-faced corrugated board having dead air spaces for insulating eifect. The several sheets comprising-the corrugated board may be composited by means of sodium silicate adhesive (not shown). Moisture-proofness of the case may be provided by means of a continuous layer I 4 of asphalt disposed between the outer facing sheet of the corrugated board and a. finishing sheet that mayalso be paper of plane surface. This asphalt is preferably of melting point of about 95 to 100 F., by the ball and ring method, and very sticky at room temperatm'e.

The package may include an inside stiffening liner 2!, such as corrugated cardboard faced on each side with paper of plane surface. The member l5 may consist of two sheets of kraft paper, with a layer of asphalt adhering the two sheets together.

The fibrous pad I0 is secured, either continuously or at intervals, to the interior faces of the case, as by means of adhesive material it.

Joints in the finished case are closed by means of paper strips ll, adhered over the joints, in

' moisture-proof manner, as by means of adhesive l8 of asphalt or the like. The asphalt, used for this sealing, is preferably rigid at atmospheric temperature and of melting point of about 170 to 240 F.

To make a tightly sealed, waterproof package, it is necessary also to seal the ends. This may be done by dipping the ends into some melted gum or pitch, adapted to provide waterproofness, and covering the dipped portion with paper. The paper is brought over the side faces and edges a short distance, as shown at 23. Also tape may be used, either in precemented form or with separately applied adhesive.

In constructing'units of the type illustrated in Figs. 1-4, there is first provideda suitable preformed, resilient lightweight and fluffy pad of felted fibers of mineral wool, of which slag wool and rock wool are two commercial types. ticularly satisfactory results have been obtained when the fibers used are rock wool. A pad of Parsuch fibers may be made by a process including finally, cutting the felt thus formed into pads of predetermined length and breadth.

A modification of the process is made for the present purpose, in thaPa small proportion of a. skeletonizing, waterproofing, and stiffening agent.

is sprayed upon the fibers, in such manner that, although used in very limited amount, .the said agent is uniformly distributed, to produce a wool which is especially light, fiufiy and resilient. Thus, there may be used an agent that is resilient and springyat ordinary temperatures, adhesive, and chemically inert towards the fibers, as, for example, an agent of the type of rosin or an asphalt having a relatively high melting point.

Apparatus and methods that may be used, with the modifications specified herein, in blowing the wool, and collecting the fibersinto the preformed felt, are described in U. S. Patent 1,899,056, issued to E. R. Powell, on February 28, 1933. p

The invention will be particularly illustrated by the example in which asphalt of the type described is the skeletonizing agent applied.

The asphalt may be sprayed into the settling chamber, at a position near the nozzle which shreds the molten rock into wool, the asphalt being either premixed with the shredding steam or supplied adjacent thereto, by means of a separate pipe. The proportion of asphalt may be small, say, of the order of 1.5 to 8 parts by weight to 100 parts of fibers. After being cooled, the integrally felted product is resilient, that is, resistant to permanent distortion when compressed slightly for a short time; and springy and selfsustaining, although weighing, in a typical bat, only about 6 pounds to the cubic foot.

The higher the melting point of the asphalt used, the more harsh and springy the finished product becomes.

The felted fibers are compressed and shaped into a bat while warm, soft and spongy, and before the skeletonizing and spacing agent has completely hardened, thereby producing a bat of predetermined size and density in which the fibers are not broken or mutilated.

There is provided, also, in form ready to be shaped into a case and to be adhered 'to the felt, corrugated paper board, cut, for example, as 11 lustrated in Fig. 2.. To adhere the felt and to aid in maintaining it in place, the inside of the case is coated with a cementing material which may be applied in the spaced stripes i6. Adhesive here used is suitably miscible, when in fluid or plastic form, with the stiffening agent present in the pad i0, so that when the pad ID is brought into contact with the adhesive on the case, there is formed an integral union or structure of the stiifening agent and adhesive. Thus, there may be used a soft asphalt, when the spacing agent in the fibers is soluble or miscible therein. In general, the adhesive may be similar chemically to the stiffening agent; for example, both may be bituminous. The adhesive is suitably somewhat tacky at atmospheric temperatures whereas the stiffening agent present should be more rigid or resilient. A soft asphalt may be used in the stripes; a hard asphalt may be' used as the stiffening agent, as stated.

After the adhesive has been applied to the cor-' rugated book wrap or folder, as, for example, as illustrated in Fig. 2, then the preformed felt ID is pressed thereupon. The cardboard'is then bent or folded at the positions indicated by the dotted lines and formed around ,the bat, to enclose it on all sides. The resiliency of the thus compressed felt causes reaction against the cardboard and facilitates adherence in the striped areas and more even spacing of the fibers in the finished unit. In view of the fact that the pads are integrally formed, it is not necessary to coat entirely the walls of the container with adhesive in order to prevent the pads from pulling apart and settling upon being subjected to subsequent jarring and mechanical vibrations. The joints in the case thus formed are then coated with a waterproof adhesive l8, as, for example, molten asphalt of high melting type, and strips of paper I! ,are applied over the coating of adhesive, to-

give complete, moisture-proof sealing of all joints and corners in the case. In the preferred method of making, the pads are cut over-sized and compressed into the containers while still warm and soft, after which they set to a satisfactory rigidity.

A unit so made contains the pad in approximately established position. Furthermore, the felt is of substantially uniform density and therefore the settling or collapse under the influence of vibration is reduced to a minimum. Moisture cannot affect the interior of the unit, inasmuch as moisture is excluded therefrom. and also because the fibers themselves are preferably moisture-proofed by the asphalt or similar water-impermeable skeletonizing agent. Furthermore, the article is draft-proof and not subject to transfer of heat by the passage of air currents inwardly through one face and outwardly through the other face.

The modification illustrated in Figs. 5-7 is useful for purposes in which evenness of spacing of the fibers of the degree obtainable in the structure illustrated in Figs. 1 to 3 is not necessary. In the modification there is used a pad of fibers and a case of the type described. A departure from the structure previously described is made, however, in that the felt 24 is secured in position, by means of stitching i9, directly to the case. The felt may be stitched by a gang sewing machine with needles spaced 3 to 5 inches apart, for instance, or the felt may be stitched thus to a separate supporting element 2|, say of corrugated cardboard, and the case then shaped around this element and the felt stitched thereto. Todecrease still further the settling of the fibers in the pad, when the pad is in use, and stabilize the size, the stitched felt may be subjected, during assembly of the unit, to jarring or jolting, to establish in part the settling thereof, and a separate felt 20 then supplied to fill the space developed by the jarring and jolting and to occupy spaces developed by the stitching, as illustrated in Figs. 6 and 7. Thus, if the bat and supporting element are jarred edgewise the space left above the upper edge of the felt would be filled by the additional felt.

Finally, the shape or closure of the case may be further established by staples 22 inserted at suitable positions, to secure together overlying portions of the casing material.

Units of the type described that have been found particularly satisfactory in the insulation of electrical refrigerators have been made of the following approximate typical .overall dimensions: 21 x 17 x 2 inches. By far the greater part of the thickness of 2 inches in such a unit corresponds to the thickness of the pad Ill of fibrous material.

The details that have been given are for the purpose of illustration, not restriction, and variations within the scope of the claim may be made without departing from the spirit of the invention.

What I claim is:

A method of making an insulating unit comprising converting molten material into mineral wool fibres, uniformly mixing with the hot fibres a binding or skeletonizing material which is a solid at normal temperatures, felting said fibres 

